Automatic compressor control system



June 21, 1932 W. E. HUGHES AUTOMATIC CO'IEIPRESSOR CONTROL SYSTEM Filed May l, 1950 .2 Sheets-Sheet l June 21, 1932. w. E. HUGHES AUTOMATIC COMPRESSOR CONTROL SYSTEM Filed May 1, 1930 2 Sheets-Sheet 2 www wm AK @n Patented June 2l, 1932 UNITED lSTATES rPATENT OFFICE WILLIAM EARL HUGHES, OF CHICAGO, ILLINOIS, ASSIG-NOR TO SULLIVAN MACHINERY COMPANY, A CORPORATION OF MASSACHUSETTS f AUTOMATIC COMPRESSOR CONTROL SYSTEM Application filed May 1,

This invention relates generally to an improved automatic control system for prime mover operated mechanisms and more particularly to an improved automatic control system for pumping mechanisms driven by a synchronous motor.

An object of my invention is to provide an improved automatic control system wherein a driving motor for a pumping mechanism, herein a iuid compressor, is adapted to operate continuously irrespective of whether the compressor isl connected to or disconnected from the prime mover. Another object is to provide an improved system Whereby a relatively close pressure regulation of the receiver pressure maybe obtained. A more specific object in this respect is to provide an improved automatic control system having a plurality of compressor units driven from a common motor preferably of the synchronous motor type. Another object is to provide an improved system and control circuit whereby the current for the control circuit may be supplied from the main line only after the driving motor is synchronized onto the line. A still further object is to provide improved control means whereby a compressor may be automatically shut down in accordance with abnormal operating conditions such as excessive temperatures of the bearings or of the compressor discharge fluid. Still another object ofthe invention is to provide improved means whereby this last function may be obtained without interfering with the operation of the motor; while a still further object in this respect is to provide improved means whereby the complete installation including the motor may be shut down in case of abnormal operating condi,

tions existing in connection with the motor, such for instance as excessive temperatures, created for example in the motor bearings, although this temperature control could be extended to any other part of themotor such as its windings. Still another and more specific object is to provide an improved push button start and/or stop control for the synchronous motor. y

Other objects and advantages of my invention will more readily be understood by perieo. seriai Np. 448,991.

Iof which are illustrated in a conventional manner merely for purposes of illustration.

In the illustrative embodiment of my invention there is shown for purposes ofillustration a prime moverppreferably a synchronous motor, adapted to drive either or both of two compressors constituting what is herein referred to as units A and B. It is very desirable to be able to operate a synchronous motor continuously, so as to maintain a high power factor, or to improve the same, but it is necessary, in order to maintain a substantially close range of receiver pressure, to load andunload the compressors, and in accordance with economy of operation it is also desirable to shut down either or both of the compressors in accordance with the demand for pressure fluid. In my improved system I have provided improved means and control circuits whereby a compressor may be unloaded when azpredetermined receiver 'pressure is obtained but still continue to be Vdriven for a predetermined interval of time, but thereafter be disconnected from the synchronous motor which continues to operate. In order to obtain the very lbest operating conditions both as to-maintainingarelatively close receiver pressure range and also tend to smooth out the load on the driving motor, the two compressor units, which may be either 'compound or single stage units, are so controlled that one unit operates between certain pressure limits and the other unit vbetween other limits, with the two pressure ranges suthcientlyoverlapping vwhereby at certain times when the demand is large both may be operated.

To accomplish the above and other functions the common synchronous driving motor l, for thetwo compressor units vA and B, issupplied withv alternating current from lines L1, L2, `and L3. To start operation of ICS the equipment, a momentary contact push button switch 2, which is normally open, is closed, whereby current flows from line L3 through Wire 3, switch 2, wire 4, contact 5, 5 solenoid coil 6 and wire 6a back to main line L2. Energization of solenoid 6k closes two sets of :contacts as by Contact bars 9 and '.10 constituting an armature. The contact bar 9 completes a holding circuitfor the solenoid 10 6 to permit release of push vbutton 2, thiscircuit comprising wires 3,11, normally closed stop push button switch 12, wire 13, contact bar 9 and fixed contact 5 'to solenoid A6, wire 6a to line L2. Current now viiow-s ,from wire 3 through wires 11, 13, bar 10, contact 14, wires .and .16, through `normally 'closed temperature :control relay switches 17, solenoid coil 18 and through wire 8 backtomain lin-eLl. Energization of coil 18 closes switch 19 vwhereupon current then `flows Jfrom wire 3 through wires 11, 13, 15, normally. closed overload relay switch 22, kwire 23, switch 19, a Awire .241to energize the main .line Aswitch 'solenoid 25, from which lthe current flows to wire 8 lback to the :main line L1. Upon energization of the solenoid Y25, the main line switch 26 'is closed, 'thereby setting upV a rotating Amagnetic field in the windings 27 ot the synchronous motor 1. .As is well 'understood, the motor :may be brought up to synchronous speed by the use of suitable means Asuch ias amortisseur windings and synchronized fonto vthe line by suitable relay conftrols for connecting the exciter to the direct current ield when the rotor has reached synchronous speed. A similar arrangement has been previously described in detail in 'an application l'of Sanford tiled November .16, 11927, Serial No. 233,695, now matured Vinto Patent No, 1,785,980, p'atented'Dee-f23, 1930. .This synchronizing icontrol is `'effected in that as soon as the main line switch 26y is 'closed the revolving magneticfield induces an alter- :rating current, iin the -motor field coils 28, Vwhich flows kthrough a closed 'circuit by way of wires 29, 3,0, .normallyfclosed :switch 31, wire 32, resistance 34, coil 36 and Ywire 37 to the other side Aof theiiield asby wire .38. This -induced current continues "as long zas there is 'relative movement between x.the eld coils `and the revolving magnetic; lfield, the ire- 'quency 1ofithis current .gradually c diminishing as the rotor .approaches synchronous fspeed. The effect of current in this circuit .is Vto `energiae `fthe Acoil 36 and Voppose the closing fof switch 39. However, when the rotor'at- -tains for sulciently approaches synchronous speed, `this current automatically dies out suciently to :allow -coil 40, which is energized after the main line switch 26 is closed as by wires 41, 42, wire 44` and wire 8 toLl, to wcl'ose Zthe switch l39. Assuming now that fthe rotor has reached :synchronous speed, :switch '39 is closed under influence of lil coil 40 and the circuit is thus established through coil 43 by way of wires 3, 7, 46, coil 43, wire 45, switch 39, wires 44 and 8 between lines L3 and L1. Energization of coil 43 automatically and simultaneously opens switch 31 and closes a switch 47 which con nects the motoreldz28 directly with the eX- citer..49 through `wires 50, 38, and 29. The motor is now synchronized on the line and is capable of carrying its full load.

Alith the motor `now operating, either Aor *both Lof the compressors may be connected thereto as by nclutches 51, 51 in accordance with the receiver pressure conditions. To control the clutch 51, which herein is of the magnetic type, but which may be of any power ope-rated type,1there is connected across the iield Ya circuit including v`wire 52, 'switch 53, which is opened whenthe clutch is disengaged, wire 54, slip rings 55 for the 'clutch magnet and wires 56 and 57 leading back to=85 wire38. There is also disposed in parallel with'ftherclutch circuit va water valveysolenoid vr58 for controlling the compressor cooling water valve 59. The solenoid 58isconnected on that iside of switch .53 whereby. 1upon .clos-.i90 ure 'of the switch the water vva'lveis `opened Y simultaneously `upon connection -o clutch 51 and 'conversely is closed-upon disconnection lof the clutch. :I

To 'controlswitch-S and effect otherdesired controlling functions such for instance as vopl-erating theclutch, with the compressor unloaded, .and subsequently actuating the Aunl'o'ader mechanism Iso asto "load the compressor, orallowingthe connected compressor tov00 lidle for. apredetermine'd time before disconnecting the clutch Vand also permitting the motor to continuously operate even alter 'the compressor is disconnected,'thereis provided alnain 'control circuit including parallel `conl' `trol .leads 69 and61 connected respectively to the main linesLZ, :and L1.V However, before ilie airain control circuit can be operative 5a switch 62 rin' line "60 must irstV be closed, and Vitisdesired that this switch shallnot be closed '-ll` until themotor is fully synchron-ized, thereby avoiding the possibility of ei'ecti'ng any vcontrol, which' might otherwisezbe the vcase due to the main control circuit beng supplied `with current from the main lin'eleads. Closure of' 115 Vswitch i162fis effected Vby .having Vits solenoid @pla-ced in parallel, as by wires 63, across the field or clutch circuit wires 52 `and 57. AItis Athus seen that switch ,625 will only be closed y'when'the iieidz28 is connected to the eXciter,at "143 whiclrstime the motor 1V s synchronized. With switch-62, manually 'operable cutout switch f64 and a normally closed switch 64a,

ywhich is-operated in accordance with certain temperaturerelay devices to be described, all l! closed, the main control functions may now be effected in accordance with the receiver pressure conditions.

VTo effect the control in accordance fwith this pressure, l`switch 65. is 'operated by .a di-ai.;

phragm or other suitable mechanism connected preferably directly to the compressor receiver R, thereby being responsive to the compressor discharge pressure. This vdiaphragm and switch are, for purposes of illustration, arranged to close when the receiver pressure is at, say, 95 pounds and to open when the receiver pressure is at, say 98 pounds. Assuming that the pressure is above 98 pounds, switch 65 is opened; as is likewise the case with switch 53; wherefore the clutch will be disconnected. However if the receiver pressure should drop to or below 95 pounds, switch 65 will close, whereupon current Hows from wire 60 through wire 66, switch 65 and thence divides between parallel wires 67 and 68 to pass through a time relay 69 and a solenoid 70 back to the other control lead 61. The sequence of operation now desired is to first connect the compressor of unit A in unloaded condition to the driving motorr and after a predetermined interval of t-ime to then load the compressor. This is effected in that upon energization of coil 70 switch 71 is opened, thereby preventing any current from flowing between control leads 60 and 61 as by way of wires 72,73 and a second time relay 74. This relay has its switch normally maintained closed whereby current can flow between the control leads 60, 61 as by way of wires 76, solenoid 77, and switch 75, thereby energizing solenoid 77 and eEecting closure of the clutch and water control valve switch 53. The clutch will thus be energized or otherwise suitably actuated so as to connect the unloaded compressor to the synchronous motor, and likewise the water valve 59 is ope-ned. To load the compressor, time relay 69 is set to close its switch 78 at a relatively short interval of time after closure of switch 65, which is simultaneous with connection of clutch 51. This time interval Jfor relay 69 is, for purposes of illustration, herein considered to be nine seconds. Upon closure of switch -7 8 current then flows between control leads 60, 61 as by way of wire 79, switch 78 and wire 8O to energize the unloader solenoid 81 thereby to load the compressor, this solenoid indieating diagrammatically any desired or usual type of unloader valve mechanism. The compressor will now pump up receiver pressure until it reaches 98 pounds, when switch 65 is opened. thereby breaking the circuit through time relay 69 and solenoid 70, whereupon switch 78 opens and switch 71 closes by gravity or by aspring if such is desired. Closure of switch 71 thereupon permits current to flow between the control leads as `by wires 72, 73 to start operation of the time relay 7 4, which is adapted to open a switch 75 after, say, a live minute interval of time. W'ith the switch 75 remaining closed, clutch control solenoid 7 7 is maintained energized and accordingly switchl 53 kept closed, thereby causing theV compressor to continue being driven even though itis unloaded. It the receiver pressure does not fall to 95 pounds before the expiration of the iive minute period as controlled by the time relay 7 4, switch 75 will thereupon be opened todeenergize solenoid 77 and accordingly open switch 53 to llikewise deenergize or so control the clutch 5l as to disconnect the compressor from the synchronous motor, while yet permitting the;

synchronous motor to continue operation. When the pressure falls` to 95 pounds the above "cycle of operations is repeated by closure of switch 65.

In case the temperature of the compressor the provision of a plurality of thermostati`` cally operated switches 82, one adapted for each of the compressor bearings, while a similar relay switch 83 is provided to be responsive to the temperature of the compressor discharge fluid, these relay switches being placed in series in a line '84 connected to line L1 and passing through solenoid of switch 64a and thence back through line 6() to line L2. It is thus seen that when the solenoid of switch 64a is deenergized due to opening of any switch 82 or 83, switch 64a will open, for instance by gravity or due to a spring, thereby opening the control lead 60. It is also seen that once the switch 64a is opened it can be only manually v reclosed due to the fact that yeven though the compressor bearings should cool down sufiiciently to permit reclosure of their relay switches 82, or should they discharge pressure fluid likewise cool sothat switch 83 i* closes, still the solenoid for switch 64a cannot be energized as there is no connected line leading back to the main line wire L2. The operator is thus compelled to manually close switch 64a and thus be reminded that the equipment should be inspected due to the presence of trouble.

lVith the main compressor control circuit broken, the synchronous motor as before stated will continue to operate, but if for any reason the motor bearings should heat excessively, either or both of the thermostatically operated motor bearing relay switches 17 will open, thereby deenergizing solenoid 18, whereby switch 19 will open by gravity or by a springif desired, thus deenergizing the solenoid 25 to permit reopening of main line switch 26 in any manner usual with switches suitable for main line circuits. The motor is thus stopped, thereby shutting down the-whole ginstallation irrespective ci the :operating conditions 'of the ivvo units.

inasmuch as :the compressor Icontrol -circuit, and elements controlled thereby, iior unit B are identical in every respect with the control circuit described for `unit A, with `vthe exception that the .pressure switch is adjusted to close at 97 .pounds .and open `at 100 pounds, the corresponding wires and :elements of the controls for units .A and B are given jthe .saine reference numbers but with primes '-.indicating unit B.

rThe -dual operation voi the two `units is as follows. After the compressor for unit A is disconnected :trom the motor due lto the receiver pressure building up to 98 pounds, ythe compressor for unit B continues to pump `iuntil' the receiver pressure reaches 100 pounds, whereupon switch 61V opens, thereby unloading the compressor and disconnecting its clutch in the same manner as withunit A. Then the areceiver.- pressure drops to 97 pounds, -switch165 closes, thereupon bringing compressor oct unit B into `actionfyibut if .the receiver `pressure continues to drop to poimds-even, while Iuni't B :is pumping, switch 165 closes, 'thereupon bringing the compres- :sorior unit A 'into service, the two units 4together then pumping up the receiver presfsnre until it reaches .98 pounds, when unit A fis disconnected, `whereupon unit B continues pumping until the receiver pressure reaches pounds, land then it also is disconnected. 4VVfhen Ait isdesired to completely .shut down the installation, including the synchronous motor, the :operator merely presses the nori-mally .closed push button switch 12 to momentarily break vthe circuit from wire 3 through 4contact arm l() and 4thereby deenergize solenoid 18 -t-o open the circuit including wires 23 Vand 24 of the vmain .switch solenoid '25.

It is Vthus Yseen :thatmy `improved arrangement is adapted .to permit continuous .operation of the synchronous motor once it is started, while the compressors are operated .only in accordance with the demand for fluid pressure thereby permitting economical op- `eration of the compressors and also improving -the power factor or maintaining .a high power factor by the continuous operation oi .the synchronous motor. In case one or the other or both of the motor bearings should become excessively heated, the corresponding thermostatically operated motor bearing relays l? will open, thereby shutting down the complete. plant. However, should compressor bearing trouble occur, or compressor vtrouble causing the discharge air to heat, the clutch will be deenergized and that unit having the trouble will come to rest without interfering with the operation oi the motor or the other unit. It is also seen that by the use of the manually operable stop switch 64, 64', either one -or both compressor units may be discontinued atthe will of the operator. The

equipment also is rendered as Ynearly .o'o'l- .prooi Yas Apossibleby the 'provision 'of ythe :solefnoid operated V.contactnr 62 iplaced in series with the main control circuit lead 60 and energized Yby being placed in .parallel with the :motor ield'circuit, thereby insuring that the motor is up tofspeed and that the field is .appliedzto the motor before there is yany possifbility oi -loadngithemoton as byconnecting eitherjof vthe magnetic clutches.

' While there :is "in this 'application ispecilicarl-ly describedfonefomn which thisinvention V'may assume :in practice, it will lbe understood tlfiat this form of the same is shown for pur- ;poses "of illustration and lthat vthe invention may be modified and lembodied in various other formswithout departingirom its Vspirit Vor the scope lof the .appended claims.

What I claim as :new Vand desire to .secure by Letters Patent is:

1. The combination comprising va continuous'ly operating motor, a mechanism 'driven therebymieans `for connectingsaid niotor and mechanism in driving relation -or -disconnecting them, and .means orautomatically dising them, 'and means .for :automatically fdisconnecting said driving rela-tion in accordance with :the .predetermined vconditions ci operation `while permitting'motor operation yto continue, said :means including temperature responsive elements, :and an electrical `circuit controlled thereby `adapted upon vioc- `currenceoffa `predetermined temperature-:c011- dition .to disconnect said driving relation, whilepermittingfmotor operation'to continue.

3. 'The vcombination Vcomprising a centinuously operating motor, a mechanism .driven thereby.means oricionnecting saidmotor and mechanism .in driving relation or vdisconne'cting them, and means for automatically disconnecting said driving relationin accord- .an'ce vwith the k.predetermined :conditions of `operation `while permitting motor operation to continue,isaid means including va temperature. responsive device .and an electrical circuit controlled thereby whereby upon 'occurrence of a predetermined temperature, .said

rinotor and driven -mechanism are both shut own.

4. The combination comprising a motor,

a plurality of mechanisms `driven thereby, means for connecting either -or both-oi said mechanisms to said motor or for disconnecting .either @or both-of .them from-said motor, and

means adapted automatically upon occurrence of predetermined operating conditions to disconnecteither or both ofsaid mechanisms so that they may stop while permitting motor operation to continue. Y l

5. The combination comprising a motor7 a plurality of pumping mechanisms driven thereby, means or connecting either or both of said mechanisms to said motor or for disconnecting either or both of them from said motor, and means adapted automatically upon occurrence of predetermined operating' conditions to disconnect either or both of said mechanisms so that they may stop while permitting motor operation to continue.

6. The combination comprising a motor, a plurality of pumping mechanisms driven thereby, means for connecting either or both of said mechanisms to said motor or for disconnecting either or both of them Jfrom said motor, and means adapted automatically upon occurrence of predetermined pressure conditions under which the compressors operate, to disconnect either or both of said mechanisms so that they may stop while permitting motor operation to continue.

7. The combination comprising an electric motor, a compressor having load controlling means, a power operated clutch mechanism for connecting said compressor and motor in driving relation, means for automatically disconnecting said clutch and allowing said compressor to stop when the compressor discharge pressure is at a predetermined value while allowing motor operation to continue,

and means whereby when the discharge pressure is at another predetermined value the clutch mechanism is reconnected while said compressor is in unloaded condition.

8. The combination comprising an electric motor, a compressor having load controlling means, a clutch mechanism for connecting said compressor and motor in driving relation, means iorV automatically disconnecting said clutch and allowing said compressor to stop when the compressor discharge 'pressure is at a predetermined value while allowing motor operation to continue, means whereby when the discharge pressure is at another predetermined value the clutch mechanism is reconnected while said compressor is in unloaded condition, and means for loading vthe compressor after the clutch has been connected for a predetermined in-` terval of time.

9. The combination comprising a synchronous motor, a plurality of compressors, clutches adapted to connect said motor and s compressors in driving relation, and means "rsi including a control circuit whereby said clutches are adapted to connect the compressors to the motor only after the motor has been synchronized.

l0. The combination comprising a synchronous motor, a compressor`,a iiuid presfor operatively connecting sure receiver therefor, a clutch for connecting said compressor in driving relation to said motor, a control circuit for said clutch,

a switch in series with said control-circuit ,Y

adapted tof be closed only when the motor has Ibeen synchronized, and means adapted upon closure of said switch and when the receiver pressure Vis at a predetermined value to eii'ect connection kof edect disconnection of the clutch when receiver` pressure is at another predetermined value, said control circuit being so arranged' that whenthe clutch is disconnected the motor is adapted to continue operation. i l1. VThe combination'V comprising a motor, a mechanism driven thereby, means for connecting said mechanism to said motor or disconnecting it therefrom while said'motor continues to'operate, means for automatically effecting operation of said iirst mentioned means to effect disconnection upon the occurrence of predetermined conditions ofA operation of said driven mechanism, and means also automatically operative but ,controlled by the operating conditions ofsaid motor for stopping the latter. y

l2. In combination, a Vdriving motor, a pump driven thereby, means for establishing or interrupting a driving connection` between said-motor and pump, Vmeans for automatically controlling said first mentioned means toeiectinterruption of the driving connection when thedischarge pressure of said clutch, and to said pump reaches and is maintained fora means operative automatically'upon the attainment of a predetermined pump discharge'V pressure forA effecting unloading of said compressor through said load controlling mech-` anism, and, after unloaded operation for va predetermined time, to interruptrthe driving connection' between the while said'motor continues to operate. l4. In combination, aV motor, a pump, means said pump to said motor for drive thereby andfor disconnecting said pump from said motor, means forlloading said pump, a pump. .discharge pressure controlled deviceysaid device controlling 'said pump .loading means and having associated therewith a time delayk apparatus delaying loading von nattainment' of Va predetermined minimum pressure, and means includin a` device for effecting disconnecting operation'V pump and motor i t said pumping mechanism,

either or both therefrom, andmeans adapted automatically upon occurrence of predetermined operating conditions to unload, or both to unload and disconnect, either or both of said mechanisms so that they Vmay s top While `permitting motor operation to continue o -`17. The combination'comprising'a motor, a plurality of pumping mechanisms "driven thereby, means for connecting either or both of said mechanisms to said motor` or disconnecting either orboth therefrom,and means adapted automatically upon occurrence of predetermined operating conditions to unload, or both to unload and disconnect, either or both of said mechanismsso that they may stop` While permitting motor operation vto continue.

gio

predetermined pressure k conditions under '18. rlh'e combination comprisingfa motor,

a plurality ofhmechanisms driven thereby, means for connect-ing either or both ,of said mechanisms to said motor lor disconnecting either or both therefrom, and means adapted automatically upony occurrenceof prede- Y termined operating conditions tounload, or

disconnect, or both to unload and disconnect, either or both of ,said` mechanisms soc-that they may stop While permitting motor operav tion to continu-e. l E u A 4 o p V519. The combination comprising a motor., a l.plurality of pumping mechanisms 'driven thereby, means (if said kmechanismsto saidmotor or disconnecting eitherfor both therefrom, and means adapted Vautomatically upon occurrence` of predetermined operating vconditions to unload, or disconnect, or both to unload and disconnect,either.or both-of said mechanisms so which the compressors operate,- to #,nload, :or both to unload fand-disconnect,either or both of Vsaid mechanisms so thatltley :may stop Whilepermitting motor-operation to continue.- In testimony whereof l yaix my sig-nature.

WILLIAM EARL HUGHES;

l'ns

for connecting `either or bothl thatthey may stop While `permit-ting motor@ operation to continue.. .t .Y Y

20.1The combination Vcomprising a motor,-

, a plurality of .pumpingmechanisms driven thereby, means for connecting either or bot-h of said .mechanisms toA saidumotor or discon-' or both therefrom, and meansnecting eitherV adapted rautomatically upon :occurrence of 

